1. Field of the Invention
The present invention relates to an improvement of the automatic winding up device of a camera, particularly to the automatic winding up device of a camera suited for the continuous photography.
2. Description of the Prior Art
Generally the winding up device of a camera is so designed that the winding up lever and the winding up stop cam operate as one body with each other in only the winding up direction by means of an one way clutch. Thus, when the winding up lever operates, the winding up stop cam is rotated through the one way clutch so as to rotate the winding up shaft and to complete the winding up operation. Thus, when the shutter is charged, the winding up stop lever becomes engageable into the groove of the winding up stop cam in such a manner that, when the shutter has been charged, the winding up stop lever engages into the groove of the winding up stop cam. When the rear shutter plane has run, releasing the shutter, the winding up stop lever gets out of the groove in the winding up cam in functional engagement with the rear shutter plane brake so that the next winding up operation becomes possible.
However, when the shutter is released while the winding up lever is maintained in a state and pressed with a force larger than a certain predetermined value in the winding up direction, the next winding up operation by means of the winding up lever often is impossible. This occurs because the winding up stop lever can not be taken out of the groove in the winding up stop cam when the force required to take the winding up stop lever out of the groove in the winding up stop cam (which is in functional engagement with the rear shutter plane brake) is smaller than that with which the winding up stop lever is pressed on the wall surface of the groove in the winding up stop cam.
However, in the case of normal photography, the photographer unconsciously allows the winding up lever to assume the initial position after the operation of the winding up lever so that the problems that the next winding up operation can not be carried out rarely occur.
However, when the winding up of the camera is automatically carried out by means of a motor driving device and so on, a large load is exercised on the above mentioned winding up stop lever and the groove in the winding up stop cam due to the mechanical winding up after the completion of the winding up operation. In this situation, it often happens that the next winding up operation is impossible.
In consequence, when, in an automatic winding up device such as a motor driving device, a sliding clutch is provided in the winding up transmission mechanism in such a manner that the eventual overload after the completion of the winding up operation is absorbed by this clutch or when an overload is exercised upon the motor, the increase of the driving current of the motor is electrically detected so as to stop the current supply to the motor and avoid the overload. However, in the former system it is necessary to provide the sliding clutch in the transmission mechanism and therefore the winding up mechanism becomes complicated. Accordingly, the mechanism can not be made compact. Also, depending upon the magnitude of the overload when the sliding begins, when an electrical load is given to the motor, the adjustment is difficult. Further in the case of the latter system, it is necessary to detect the overcurrent level of the motor and therefore it is necessary to provide the level detecting circuit whereby the adjustment of the set level is not an easy task in the same way as in the case of the former system. Also, when there takes place any load having nothing to do with the winding up operation, such load is also detected in such a manner that the winding up operation is interrupted.
A purpose of the present invention therefore is to eliminate the above mentioned shortcomings, by keeping the winding up motor in the conductive state for a certain time after the completion of the winding up operation so as to overdrive the motor and to produce a reaction in the winding up mechanism of the camera so that the continuous photography can be carried out.
Another purpose of the present invention is to provide the winding up motor with a short circuit for braking with the one way conductive efficiency so as to exercise the braking effect of the motor while the backward running of the motor is made easy due to the reaction of the winding up mechanism.
A further purpose of the present invention is to make the photographic interval shorter by making the release operation possible before the completion of the operation of the winding up motor at the time of continuous photography.
A still further purpose of the present invention is to make the self-timer serve at the same time as the timer for forming the interval time from the completion of the winding up operation till the start of the release operation.
Other purposes of the present invention will be disclosed from the explanations to be made below in detail in accordance with the embodiment of the present invention.